The present invention relates to an electrophotographic copying machine and, more particularly, to a device for detecting the opening of a document cover above a document table for an electrophotographic copying machine.
An electrophotographic copying machine produces an electrostatic latent image on an optical-sensitive member. The latent image corresponds to an image on a copy document such as a manuscript or book to be copied. Toner particles are electrically adhered to the latent image, so that the latent image becomes visible to form a toner image. The toner image is transferred onto a copy paper via a transference charger.
Conventionally, the copy document is disposed on a document table on which a document cover is provided for being able to cover the copy document when the copy document is subject to optical scanning. The document cover is pivotally secured to make the copy document opened and closed. The document cover serves to press the document upon the document table and to seal scanning light beneath the document cover.
Some electrophotographic copying machines provide the scanning light by detecting the closing of the document cover, so as to execute the copying operation.
To detect the closing of the document cover, a lead switch means is conventionally provided whose contacts are closed by pivotally closing the document cover. Unless the document cover is completely closed, the lead switch contacts are not closed. In some instances, the copy document is too thick to permit the document cover to be completely closed. In such a case, as the lead switch contacts are opened, it is detected that the document cover is opened, so that the copying machine may not be operated.
Therefore, it is desired to provide an improved detection device for detecting the opening and the closing of the document cover on the document table.